package com.example.fangyh09.calculator;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity implements View.OnClickListener{
    Button btn_0;
    Button btn_1;
    Button btn_2;
    Button btn_3;
    Button btn_4;
    Button btn_5;
    Button btn_6;
    Button btn_7;
    Button btn_8;
    Button btn_9;
    Button btn_point;
    Button btn_clear;
    Button btn_del;
    Button btn_plus;
    Button btn_minus;
    Button btn_multiply;
    Button btn_divide;
    Button btn_equal;
    EditText et_input;
    boolean getAns;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getAns = false;
        btn_0 = (Button)findViewById(R.id.btn_0);
        btn_1 = (Button)findViewById(R.id.btn_1);
        btn_2 = (Button)findViewById(R.id.btn_2);
        btn_3 = (Button)findViewById(R.id.btn_3);
        btn_4 = (Button)findViewById(R.id.btn_4);
        btn_5 = (Button)findViewById(R.id.btn_5);
        btn_6 = (Button)findViewById(R.id.btn_6);
        btn_7 = (Button)findViewById(R.id.btn_7);
        btn_8 = (Button)findViewById(R.id.btn_8);
        btn_9 = (Button)findViewById(R.id.btn_9);
        btn_point = (Button)findViewById(R.id.btn_point);
        btn_clear = (Button)findViewById(R.id.btn_clear);
        btn_del = (Button)findViewById(R.id.btn_del);
        btn_plus = (Button)findViewById(R.id.btn_plus);
        btn_minus = (Button)findViewById(R.id.btn_minus);
        btn_multiply = (Button)findViewById(R.id.btn_multiply);
        btn_del = (Button)findViewById(R.id.btn_del);
        btn_divide = (Button)findViewById(R.id.btn_divide);
        btn_equal = (Button)findViewById(R.id.btn_equal);

        et_input = (EditText)findViewById(R.id.et_input);


        btn_0.setOnClickListener(this);
        btn_1.setOnClickListener(this);
        btn_2.setOnClickListener(this);
        btn_3.setOnClickListener(this);
        btn_4.setOnClickListener(this);
        btn_5.setOnClickListener(this);
        btn_6.setOnClickListener(this);
        btn_7.setOnClickListener(this);
        btn_8.setOnClickListener(this);
        btn_9.setOnClickListener(this);
        btn_point.setOnClickListener(this);
        btn_clear.setOnClickListener(this);
        btn_del.setOnClickListener(this);
        btn_plus.setOnClickListener(this);
        btn_minus.setOnClickListener(this);
        btn_multiply.setOnClickListener(this);
        btn_divide.setOnClickListener(this);
        btn_equal.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        String str = et_input.getText().toString();
        switch (v.getId()) {
            case R.id.btn_0:
            case R.id.btn_1:
            case R.id.btn_2:
            case R.id.btn_3:
            case R.id.btn_4:
            case R.id.btn_5:
            case R.id.btn_6:
            case R.id.btn_7:
            case R.id.btn_8:
            case R.id.btn_9:
            case R.id.btn_point:
                if (getAns) {
                    str = "";
                    getAns = false;
                }
                et_input.setText(str + ((Button) v).getText());
                break;
            case R.id.btn_plus:
            case R.id.btn_minus:
            case R.id.btn_multiply:
            case R.id.btn_divide:
                if (getAns) {
                    str = "";
                    getAns = false;
                }
                et_input.setText(str + " " + ((Button) v).getText() + " ");
                break;
            case R.id.btn_clear:
                et_input.setText("");
                break;
            case R.id.btn_del:
                if (str != null && !str.equals("")) {
                    et_input.setText(str.substring(0,str.length() - 1));
                }
                break;
            case R.id.btn_equal:
                getResult();
                getAns = true;
                break;

        }
    }
    private void getResult() {

        String exp = et_input.getText().toString();
        if (exp == null || exp.equals("")) {
            return;
        }
        if (!exp.contains(" ")) {
            return;
        }

        String s1 = exp.substring(0,exp.indexOf(" "));
        String op = exp.substring(exp.indexOf(" ") + 1,exp.indexOf(" ") + 2);
        String s2 = exp.substring(exp.indexOf(" ") + 3);
        if (s1.equals("")) {
            s1 = "0";
        }
        double result = 0;
        if (!s2.equals("")) {
            double d1 = Double.parseDouble(s1);
            double d2 = Double.parseDouble(s2);
            if (op.equals("+")) {
                result = d1 + d2;
            }
            else if(op.equals("-")) {
                result = d1 - d2;
            }
            else if(op.equals("*")) {
                result = d1 * d2;
            }
            else {
                if (d2 == 0) {
                    result = 0;
                }
                else {
                    result = d1 / d2;
                }
            }
            if (!s1.contains(".") && !s2.contains(".") && !op.equals("/")) {
                int r = (int) result;
                et_input.setText(r + "");
            }
            else {
                et_input.setText(result + "");
            }
        }
        else if(!s1.equals("") && s2.equals("")) {
            et_input.setText(exp);
        }
        else {
            et_input.setText("");
        }
    }
}
























































































